Aircraft air duct system for transmitting electrical power and visible light

ABSTRACT

An air duct system comprising an air duct having a main body, a visible light source, and one or more photovoltaic devices. The main body of the air duct defines a passageway having a reflective inner surface. The visible light source is configured to generate visible light, where the visible light source directs the visible light along the reflective inner surface of the air duct. The one or more photovoltaic devices are disposed along the reflective inner surface of the air duct, where a portion of the visible light generated by the visible light source is converted into electrical power by the one or more photovoltaic devices.

INTRODUCTION

The present disclosure relates to an air duct system. More particularly,the present disclosure is directed towards an air duct system configuredto transmit air, visible light, and electrical power.

BACKGROUND

There is an ongoing effort to reduce the weight of an aircraft. Areduction in weight typically results in a corresponding reduction infuel consumption of the aircraft and may also allow for an increase inpayload capacity. Electrical power, current, and electronic signals aretypically conducted through wires or cables constructed of copper oraluminum as the conductive medium. For example, wiring is used in thepassenger cabin of the aircraft to power various electronic devices suchas, for example, overheard lighting and displays. However, wiringcontributes significantly to the total weight of the aircraft.

SUMMARY

According to several aspects, an air duct system is disclosed. The airduct system includes an air duct having a main body, where the main bodyof the air duct defines a passageway having a reflective inner surface.The air duct system also includes a visible light source configured togenerate visible light. The visible light source directs the visiblelight along the reflective inner surface of the air duct. The air ductsystem also includes one or more photovoltaic devices disposed along thereflective inner surface of the air duct, where a portion of the visiblelight generated by the visible light source is converted into electricalpower by the one or more photovoltaic devices.

In another aspect, an air duct system is disclosed. The air duct systemincludes an air duct having a main body, where the main body of the airduct defines a passageway having a reflective inner surface. The airduct system also includes a visible light source configured to generatevisible light, where the visible light source directs the visible lightalong the reflective inner surface of the air duct. The air duct systemfurther includes an emitter configured to emit radio frequency waves,where the emitter directs the radio frequency waves along the reflectiveinner surface of the air duct. Finally, the air duct system includes oneor more antennas that are each connected to a corresponding powerharvesting circuit, where the radio frequency waves are received by theone or more antennas and are converted into electrical power by thecorresponding power harvesting circuit.

In still another aspect, a method for transmitting air, visible light,and electrical power through an air duct of an aircraft is disclosed.The method includes receiving, by the air duct, conditioned air andvisible light. The method also includes directing the visible lightalong a reflective inner surface of the air duct, where the visiblelight reflects off of the reflective inner surface and travels along apassageway of the air duct. Finally, the method includes converting aportion of the visible light into electrical power by one or morephotovoltaic devices disposed along the reflective inner surface of theair duct.

In another aspect, an air duct system is disclosed. The air duct systemincludes an air duct having a main body, where the main body of the airduct defines a passageway and an outer surface. The air duct system alsoincludes one or more thermoelectric generators, where eachthermoelectric generator includes a hot side and a cold side, and thehot side of the thermoelectric generator is positioned along the outersurface of the air duct.

The features, functions, and advantages that have been discussed may beachieved independently in various embodiments or may be combined inother embodiments further details of which can be seen with reference tothe following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a perspective, partially sectioned view of an aircraft withthe disclosed air duct system, according to an exemplary embodiment;

FIG. 2 is a schematic diagram of the air duct system including a visiblelight source and one or more photovoltaic devices configured totransform visible light into electrical power, according to an exemplaryembodiment;

FIG. 3 is a schematic diagram of a single beam of visible light beingtransmitted by the visible light source, according to an exemplaryembodiment;

FIG. 4 is an alternative embodiment of the air duct system in FIG. 2having a radio frequency emitter, one or more antennas, and one or morepower harvesting circuits, according to an exemplary embodiment;

FIG. 5 is a schematic diagram of the power harvesting circuit shown inFIG. 4, according to an exemplary embodiment;

FIG. 6A illustrates a thermoelectric generator disposed along an outersurface of the air duct, where the thermoelectrical generator cooled bynatural convection, according to an exemplary embodiment;

FIG. 6B illustrates the thermoelectric generator in FIG. 6A cooled byforced convection, according to an exemplary embodiment;

FIG. 6C illustrates the thermoelectric generator cooled by conduction,according to an exemplary embodiment;

FIG. 6D illustrates the thermoelectric generator disposed along anotherembodiment of the air duct only transmitting the conditioned air,according to an exemplary embodiment;

FIG. 7 is another embodiment of the air duct system shown in FIG. 2further including an ultraviolet light source, according to an exemplaryembodiment;

FIG. 8 is a schematic diagram of another embodiment of the air ductsystem including only the ultraviolet light source, according to anexemplary embodiment;

FIG. 9 is a process flow diagram illustrating a method for transmittingair, visible light, and electrical power by the disclosed air duct,according to an exemplary embodiment; and

FIG. 10 is a process flow diagram illustrating a method for sanitizingair flowing through the disclosed air duct, according to an exemplaryembodiment.

DETAILED DESCRIPTION

The present disclosure is directed towards an air duct system configuredto transmit air, visible light, and electrical power to passengers in avehicle, such as an aircraft. The air duct system includes an air ductthat defines a passageway having a reflective inner surface and avisible light source that directs visible light along the reflectiveinner surface of the air duct. The disclosed air duct system alsoincludes one or more photovoltaic devices disposed along the reflectiveinner surface of the air duct. A portion of the visible light generatedby the visible light source is converted into electrical power by thephotovoltaic device. Accordingly, the disclosed air duct systemtransmits electrical power without utilizing wiring or cables. In anembodiment, the disclosed air duct system is used to transmit visiblelight to the overhead lights in an aircraft, and the electrical powerfrom the photovoltaic devices is used to provide electrical power to anelectronic device such as a television display. The disclosed air ductsystem does not require wiring to transmit electrical power to theoverhead lighting and the television display in the interior cabin of anaircraft, and results in a significant reduction in weight.

In an embodiment, the disclosed air duct system includes an ultravioletlight source that emits ultraviolet light. The ultraviolet light isconfigured to sanitize the air flowing through the passageway of the airduct by killing airborne bacteria and other germs that are suspendedwithin the air flowing through the air duct. In an embodiment, theultraviolet light source is utilized in combination with the visiblelight source. Alternatively, in another embodiment, the ultravioletlight source is used alone.

In still another embodiment, the disclosed air duct system onlytransmits air. In other words, no visible light or ultraviolet light istransmitted through the air duct. Instead, the air duct includes one ormore thermoelectric generators disposed along an outer surface of theair duct. The thermoelectric generator is configured to transform heatalong the outer surface of the air duct into electrical energy that maybe used by one or more systems in the aircraft.

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

Referring to FIG. 1, a partially cross-sectioned aircraft 10 is shown.The aircraft 10 includes a fuselage 12, a pair of wings 14, a nacelle 16mounted to each wing 14, a main engine 18 housed within each nacelle 16(only one of the main engines 18 are shown), and an air duct system 20.The air duct system 20 includes an overhead air duct 22 and a pluralityof distribution ducts 24. Outside air 32 enters the main engine 18through an inlet 34 and is compressed and heated by a compressor section28 of the main engine 18 into heated pressurized air. A portion of theheated pressurized air from the compressor sections 28 of the mainengine 18, which is referred to as bleed air, is cooled and then remixedwith recirculated air to create conditioned air 36. The conditioned air36 is set to a predetermined temperature. The conditioned air 36 flowsthrough the overhead air duct 22, to the distribution ducts 24, and isdelivered throughout an interior cabin 58 (FIG. 2) of the aircraft 10.

In the non-limiting embodiment as shown in FIG. 1, the overhead air duct22 is linear and extends along a centerline C of the aircraft 10.However, it is to be appreciated that the overhead air duct 22 mayinclude a non-linear or curved profile as well. Moreover, although thefigures illustrate the disclosed air duct system 20 as part of anaircraft, the air duct system 20 may be used in other applications aswell.

FIG. 2 is a schematic diagram of an embodiment of the air duct system 20for transmitting visible light L and electrical energy. As explainedbelow, the disclosed air duct system 20 is configured to transmit air,visible light, and electrical power. Specifically, a portion of thevisible light L is transformed into electrical power. In anotherembodiment, the disclosed air duct system 20 includes an ultravioletlight source 30 (seen in FIG. 7) that exposes the conditioned air 36flowing through the overhead air duct 22 to ultraviolet light. Theultraviolet light emitted by the ultraviolet light source 30 is of afrequency or intensity sufficient to sanitize air.

Turning back to FIG. 2, the air duct system 20 includes an air duct 40having a main body 42. The main body 42 of the air duct 40 defines apassageway 44 having a reflective inner surface 46, where theconditioned air 36 and the visible light L are transmitted through thepassageway 44. The reflective inner surface 46 of the main body 42 ofthe air duct 40 includes a reflectance of at least fifty percent. Forexample, an aluminum coating would provide a reflectance of at leastfifty percent. However, in an embodiment the reflective inner surface 46of the main body of the air duct 40 includes a reflectance of at leastninety-nine percent. One example of a material for coating thereflective inner surface 46 of the air duct 40 that has a reflectance ofat least ninety-nine percent is a reflective film. In an embodiment, thereflective film is applied to the air duct 40 during fabrication. In analternative embodiment, a conventional air duct system is retrofitted byapplying the reflective film to the inner surface of the conventionalair duct. One commercially available example of a reflective film isSpecular Film DF2000MA, which is available from the 3M Company ofMaplewood, Minn. In another embodiment, the reflective inner surface 46is coated with an optical supermirror, a Bragg grating, photoniccrystal, or a nanostructured materials. A Bragg grating is a reflectingstructure having a periodic refractive index modulation.

The air duct system 20 also includes a visible light source 48configured to generate the visible light L, where the visible lightsource 48 directs the visible light L along the reflective inner surface46 of the air duct 40. The visible light L then impinges against thereflective inner surface 46 and travels along the passageway 44 of theair duct 40. In one embodiment, the visible light source 48 ispositioned at an end 50 of the air duct 40 situated at the front end 52of the aircraft 10 (FIG. 1). However, it is to be appreciated that theposition of the visible light source 48 is not limited to thisconfiguration as long as the visible light L is directed towards thereflective inner surface 46 of the air duct 40 and is transmitted alonga length 66 of the air duct 40. In one non-limiting embodiment, thevisible light source 48 includes an array of light-emitting diodes(LEDs) 54. In an embodiment, the LEDs 54 emit white light at tenkilowatts, however, it is to be appreciated that other types of devicesthat emit visible light may be used as well. Furthermore, it is also tobe appreciated that the visible light L is not limited to only whitelight. Instead, the visible light L may be of any color and intensitythat is required for a particular application.

FIG. 3 is an illustration of a light beam 56 emitted from a lamp 60. Thelamp 60 is part of an array 62 of lamps 60 that are the visible lightsource 48. For purposes of clarity, only one of lamps 60 is emittingvisible light L in FIG. 3. In an embodiment, the lamps 60 are parabolicaluminized reflector lamps, however, it is to be appreciated that othertypes of lamps may be used as well. The light beam 56 issemi-culminated, which means that the light beam 56 emitted from thevisible light source 48 (i.e., the lamps 60) has an angle of divergenceθ of ten degrees or less. The angle of divergence θ represents theamount of angular spread that the light beam 56 undergoes as thedistance d from the visible light source 48 increases. As seen in FIG.3, the light beam 56 diverges away from a center diameter D, where thecenter diameter D represents a maximum intensity 68 of the light beam56. The light beam 56 is semi-culminated so as to direct the visiblelight L along the reflective inner surface 46 of the air duct 40.

Referring back to FIG. 2, the air duct system 20 further includes one ormore of lighting apertures 72 disposed along the main body 42 of the airduct 40, where a portion of the visible light L generated by the visiblelight source 48 exits the air duct 40 through the lighting apertures 72.The lighting apertures 72 each represent the overhead light for apassenger located within the interior cabin 58 of the aircraft 10 (FIG.1). Accordingly, the lighting apertures 72 replace a traditional lampthat is used to provide visible light to a passenger. The lightingapertures 72 also eliminate the need to route wiring or cables throughthe air duct 40 as well, which in turn reduces weight in the aircraft10. The air duct 40 further includes one or more air valves 74 disposedalong the main body 42 of the air duct 40. The air valves 74 are eachconfigured to release the conditioned air 36 (FIG. 1) that travelsthrough the air duct system 20.

Continuing to refer to FIG. 2, the air duct system 20 also includes oneor more photovoltaic devices 76 that are disposed along the reflectiveinner surface 46 of the air duct 40. A portion of the visible light Lgenerated by the visible light source 48 impinges against eachphotovoltaic device 76 and is then converted into electrical power bythe photovoltaic devices 76. In the embodiment as shown, eachphotovoltaic device 76 provides electrical power to a correspondingelectronic device 78. In an embodiment, an individual electronic device78 is provided for each passenger in the aircraft 10. For example, inone embodiment, the electronic device 78 is a television display that isprovided to each passenger seated within the interior cabin 58 of theaircraft 10. Some examples of photovoltaic devices 76 include, but arenot limited to, crystalline silicon photovoltaic devices having anefficiency of about 25%, multi-junction photovoltaic devices having anefficiency of about 45%, and perovskite photovoltaic devices. Since thesilicon photovoltaic devices produce less electrical power, they may beused in lower-cost application.

As seen in FIG. 2, a single lighting aperture 72, a single air valve 74,a single photovoltaic device 76, and a single electronic device 78 areprovided for each passenger of the aircraft 10. However, in anotherembodiment, the power from multiple photovoltaic devices 76 are combinedtogether to provide power to a single electronic device 78 requiringmore electrical energy than a single electronic device allotted to apassenger, such as a television screen. For example, in anotherembodiment, the power generated from a plurality of the photovoltaicdevices 76 are combined together to provide power to an electronicdevice such as a microwave.

Although FIG. 2 illustrates photovoltaic devices 76 for transforming thevisible light L into electrical energy, in one embodiment thephotovoltaic devices 76 are omitted. Instead, as shown in FIG. 4, thephotovoltaic devices 76 are replaced by an antenna 80 and a powerharvesting circuit 82. In the embodiment as shown in FIG. 4, the airduct system 20 further includes an emitter 84 configured to emit radiofrequency waves 86. The emitter 84 directs the radio frequency waves 86along the reflective inner surface 46 of the air duct 40. The radiofrequency waves 86 impinge against the reflective inner surface 46 ofthe air duct 40 and are intercepted by one of the antennas 80. It is tobe appreciated that the reflective inner surface 46 of the air duct 40reflects the radio frequency waves 86. Therefore, the radio frequencywaves 86 travel through the air duct 40 and are not transmitted to othersurrounding components of the aircraft 10. As seen in FIG. 4, theantennas 80 each extend partially into the passageway 44 of the air duct40. Therefore, the antennas 80 are each positioned to intercept theradio frequency waves 86 that travel through the air duct 40.

The antennas 80 are each connected to a corresponding power harvestingcircuit 82, where the radio frequency waves 86 are received by theantennas 80 and are converted into electrical power by the correspondingpower harvesting circuits 82. FIG. 5 is a schematic diagram illustratingan embodiment of the power harvesting circuit 82. In the embodiment asshown in FIG. 5, the power harvesting circuit 82 includes an impedancematching network 90, a combined rectifier and voltage multiplier 92, anda power management module 94. The impedance matching network 90 isconfigured to transform the impedance of the antenna 80 into atransmission impedance of the power harvesting circuit 82. The combinedrectifier and voltage multiplier 92 is configured to convert the radiofrequency waves 86 into DC power, which provides the voltage required bythe electronic devices 78. The power management module 94 stores theelectrical energy and provides the electrical energy to thecorresponding electronic device 78. Turning back to FIG. 4, it is to beappreciated that since the visible light source 48 is not used totransmit electrical energy, the visible light L may be less intense whencompared to a visible light source 48 for transmitting both electricalpower and visible light.

FIGS. 6A-6D illustrate yet another embodiment of the air duct system 20including one or more thermoelectric generators 100 disposed along anouter surface 102 of the air duct 40. It is to be appreciated that heatis generated as the visible light L impinges against the reflectiveinner surface 46 of the air duct 40. Heat is also produced when theradio frequency waves 86 (seen in FIG. 4) or the ultraviolet light U(seen in FIG. 7) impinges against the reflective inner surface 46 of theair duct 40 as well. The thermoelectric generator 100 is configured totransform the heat into electrical energy that may be used by one ormore systems in the aircraft 10. The thermoelectric generator 100 is athermoelectric module, such as a solid state thermoelectric module.

The thermoelectric generator 100 includes a heat sink 104 (in theembodiment as shown in FIG. 6C, the heat sink 104 is omitted). Thethermoelectric generator 100 also includes a hot side 106 and a coldside 108. The hot side 106 of the thermoelectric generator 100 ispositioned along the outer surface 102 of the air duct 40. In anembodiment, the thermoelectric generator 100 is physically attached toouter surface 102 of the air duct 40 by adhesives or mechanicalattachments such as screws or brackets (not shown). The cold side 108 ofthe thermoelectric generator 100 opposes the hot side 106 of thethermoelectric generator 100 and contacts the heat sink 104. It is to beappreciated that the terms hot and cold are intended to describerelative temperatures of the thermoelectric generator 100. Consequently,when the outer surface 102 of the air duct heats the hot side 106 of thethermoelectric generator 100 to a temperature greater than the cold side108 an electric current is produced.

The thermoelectric generator 100 is cooled by natural convection, forcedconvection, or solid conduction. In the embodiment as shown in FIG. 6A,the thermoelectric generator 100 is cooled using natural convention.Specifically, outside air 110 (which is relatively cold) flows over theheat sink 104 of the thermoelectric generator 100. In the embodiment asshown in FIG. 6B, the thermoelectric generator 100 is cooled usingforced convention. Specifically, the outside air 110 is channeled overthe heat sink 104 of the thermoelectric generator 100 by a tube 112. Inthe embodiment as shown in FIG. 6C, the thermoelectric generator 100 iscooled using solid conduction. Specifically, a solid 114 having a highthermal conductivity is used to connect the cold side 108 of thethermoelectric generator 100 with the outside air 110. Some examples ofsolids having a high thermal conductivity include, but are not limitedto, aluminum, graphene, and single wall carbon nanotubes. In anotherembodiment, the solid 114 is a heat pipe. A heat pipe is a two phaseheat transfer device including an envelope, a working fluid, and a wickstructure.

Turning now to FIG. 6D, in another embodiment the air duct 40 does notinclude the ultraviolet light source 30 (FIG. 7), the visible lightsource 48 (FIG. 2), or the emitter 84 (FIG. 4). Instead, the air duct 40transmits the conditioned air 36. However, the outer surface 102 isstill heated to a temperature that is greater than the outside air 110.Thus, a temperature differential still exists between the hot side 106and the cold side 108 of the thermoelectric generator 100 sufficient togenerate electric current.

FIG. 7 illustrates yet another embodiment of the air duct 40 includingthe ultraviolet light source 30 configured to generate the ultravioletlight U. The source of ultraviolet light source 30 may be, for example,an ultraviolet laser or a low-pressure ultraviolet lamp. The ultravioletlight source 30 directs the ultraviolet light U along the reflectiveinner surface 46 of the air duct 40, where the ultraviolet light Usanitizes the conditioned air 36 flowing through the overhead air duct22 is sanitized. In other words, the ultraviolet light U kills airbornegerms, bacteria, and other contaminates that are suspended within theconditioned air 36 that flows through the air duct 40. The ultravioletlight U includes a germicidal wavelength ranging from 185 to 400nanometers (nm). The germicidal wavelength range includes nearultraviolet wavelengths of about 220 nm to about 400 nm and farultraviolet wavelengths of about 190 nm to about 220 nm. The power ofthe ultraviolet light source 30 may vary based on the size of the airduct 40, airflow rate, and the power of the ultraviolet light source 30,and in one embodiment may range from 100 Watts to 1 Kilowatt.

Continuing to refer to FIG. 7, the air duct system 20 further includes aplurality of ultraviolet optical filters 120 placed over each of theplurality of lighting apertures 72. The ultraviolet optical filters 120allows for the visible light L to enter the interior cabin 58 and at thesame time filters the ultraviolet light U. This is to preventultraviolet light expose to the passengers located in the interior cabin58 of the aircraft 10. The air duct system 20 also includes a pluralityof ultraviolet optical filters 122 placed over each of the plurality ofair valves 74 as well. The ultraviolet optical filters 122 areconfigured to allows for the conditioned air 36 to flow to the interiorcabin 58. In an embodiment, the ultraviolet optical filters 120, 122 areconstructed of a glass that is opaque to wavelengths in the germicidalwavelength.

Although FIG. 7 illustrates both the ultraviolet light source 30 and thevisible light source 48, in another embodiment the ultraviolet lightsource 30 is used alone. Referring now to FIG. 8, the air duct system 20includes only the ultraviolet light source 30 to sanitize theconditioned air 36. Since the air duct system 20 in FIG. 8 does nottransmit visible light, the inner reflective surface 46 does not requirea relatively high reflectance that is described above (i.e., areflectance of ninety-nine percent). Instead, the inner reflectivesurface 46 of the main body 42 of the air duct 40 includes a reflectanceof at least twenty-five percent.

FIG. 9 is an exemplary process flow diagram illustrating a method 300transmitting air, visible light, and electrical power through the airduct 40 of the aircraft 10. Referring to FIGS. 1, 2, and 9, the method300 begins at block 302. In block 302, the air duct 40 receives theconditioned air 36 and visible light L. As mentioned above, the visiblelight L is generated by the visible light source 48. The method 300 maythen proceed to block 304.

In block 304, the visible light L is directed along the reflective innersurface 46 of the air duct 40, where the visible light L reflects off ofthe reflective inner surface 46 and travels along the passageway 44 ofthe air duct 40. The method 300 may then proceed to block 306.

In block 306, a portion of the visible light L is converted intoelectrical power by one or more photovoltaic devices 76 disposed alongthe reflective inner surface 46 of the air duct 40. As mentioned above,the photovoltaic device 76 provides electrical power to a correspondingelectronic device 78. The method 300 may then proceed to block 308.

In block 308, a portion of the visible light L is allowed to exit theair duct 40 through one or more lighting apertures 72 disposed along themain body 42 of the air duct 40. The method 300 may then proceed toblock 310.

In block 310, the conditioned air 36 is released by one or more airvalves 74 disposed along the main body 42 of the air duct 40. The method300 may then proceed to block 312.

It is to be appreciated that block 312 is optional and may be omitted insome instances. In block 312, the ultraviolet light U (seen in FIG. 7)is directed along the reflective inner surface 46 of the air duct 40. Asmentioned above, the ultraviolet light U includes a germicidalwavelength ranging from 185 to 400 nanometers. The method 300 may thenterminate or, alternatively, proceed back to block 302.

Referring to FIGS. 1-7 and 9, the disclosed air duct system isconfigured to provide conditioned air, visible light, and electricalpower. The electrical power is transmitted through the air duct in theform of visible light and is transformed into electrical power byphotovoltaic devices. As a result, there is no wiring or cables totransmit electrical power to the overhead lights in an aircraft.Moreover, the photovoltaic devices provide electrical power to otherelectronic devices, such as individual television screens for eachpassenger. Accordingly, there is no wiring or cables included fortransmitting electrical power to various electronic devices in theaircraft. This results in a significant weight savings, which in turnenhances fuel efficiency.

As mentioned above, in the embodiment as shown in FIG. 8, theultraviolet light source 30 is used alone (i.e., without the visiblelight source 48). Turning now to FIG. 10, a process flow diagramillustrating a method 400 for sanitizing the conditioned air 36 in anaircraft 10. Referring now to FIGS. 8 and 10, the method 400 begins atblock 402. In block 402, the air duct 40 receives the conditioned air 36and ultraviolet light U. As mentioned above, the visible light L isgenerated by the ultraviolet light source 30. The method 300 may thenproceed to block 404.

In block 404, the ultraviolet light U is directed along the reflectiveinner surface 46 of the air duct 40, where the ultraviolet light Ureflects off of the reflective inner surface 46 and travels along thepassageway 44 of the air duct 40, and sanitizes the conditioned air 36flowing through the air duct 40. The method 300 may then proceed toblock 406.

In block 406, the conditioned air 36 is released by one or more airvalves 74 disposed along the main body 42 of the air duct 40. Asmentioned above, the ultraviolet optical filters 122 is placed over theair valves 74 to prevent the transmission of the ultraviolet light U.The method 400 may then proceed to block 408.

In block 408, a portion of the ultraviolet light U is allowed to exitthe air duct 40 through one or more lighting apertures 72 disposed alongthe main body 42 of the air duct 40. As mentioned above, a plurality ofultraviolet optical filters 120 are placed over the lighting apertures72 to prevent the ultraviolet light U from traveling into the interiorcabin 58 of the aircraft 10. The method 400 may then proceed terminateor proceed back to block 402.

Referring to FIGS. 8 and 10, the disclosed air duct system provides alightweight approach for sanitizing the conditioned air throughout theinterior cabin of an aircraft. This in turn prevents the transmission ofinfectious diseases that may occur among air travelers. In anembodiment, the ultraviolet light may kill some types of seriousinfectious diseases as well.

The description of the present disclosure is merely exemplary in natureand variations that do not depart from the gist of the presentdisclosure are intended to be within the scope of the presentdisclosure. Such variations are not to be regarded as a departure fromthe spirit and scope of the present disclosure.

What is claimed is:
 1. An air duct system, comprising: an air ducthaving a main body, wherein the main body of the air duct defines apassageway having a reflective inner surface; a visible light sourceconfigured to generate visible light, wherein the visible light sourcedirects the visible light along the reflective inner surface of the airduct; and one or more photovoltaic devices disposed along the reflectiveinner surface of the air duct, wherein a portion of the visible lightgenerated by the visible light source is converted into electrical powerby the one or more photovoltaic devices.
 2. The air duct system of claim1, further comprising one or more lighting apertures disposed along themain body of the air duct, wherein a portion of the visible lightgenerated by the visible light source exits the air duct through the oneor more lighting apertures.
 3. The air duct system of claim 2, furthercomprising an ultraviolet light source configured to generateultraviolet light, wherein the ultraviolet light source directs theultraviolet light along the reflective inner surface of the air duct. 4.The air duct system of claim 3, further comprising one or moreultraviolet optical filters, wherein an ultraviolet optical filter isplaced over each of the one or more lighting apertures.
 5. The air ductsystem of claim 4, wherein the ultraviolet light includes a germicidalwavelength ranging from 185 to 400 nanometers.
 6. The air duct system ofclaim 1, further comprising one or more air valves disposed along themain body of the air duct.
 7. The air duct system of claim 1, whereinthe visible light source comprises an array of light-emitting diodes(LEDs).
 8. The air duct system of claim 1, wherein the visible lightemitted from the visible light source has an angle of divergence of tendegrees or less.
 9. The air duct system of claim 1, wherein thereflective inner surface of the main body of the air duct includes areflectance of at least fifty percent.
 10. The air duct system of claim1, wherein the reflective inner surface of the main body of the air ductincludes a reflectance of at least ninety-nine percent.
 11. The air ductsystem of claim 1, further comprising a thermoelectric generator havinga hot side and a cold side, wherein the hot side of the thermoelectricgenerator is positioned along an outer surface of the air duct.
 12. Theair duct system of claim 11, wherein the thermoelectric generator iscooled by natural convection, forced convection, or solid conduction.13. A method for transmitting air, visible light, and electrical powerthrough an air duct of an aircraft, the method comprising: receiving, bythe air duct, conditioned air, and visible light; directing the visiblelight along a reflective inner surface of the air duct, wherein thevisible light reflects off of the reflective inner surface and travelsalong a passageway of the air duct; and converting a portion of thevisible light into electrical power by one or more photovoltaic devicesdisposed along the reflective inner surface of the air duct.
 14. Themethod of claim 13, further comprising: allowing a portion of thevisible light to exit the air duct through one or more lightingapertures disposed along a main body of the air duct.
 15. The method ofclaim 13, further comprising: releasing the conditioned air by one ormore air valves disposed along a main body of the air duct.
 16. Themethod of claim 13, further comprising: directing ultraviolet lightalong the reflective inner surface of the air duct.
 17. The method ofclaim 16, wherein the ultraviolet light includes a germicidal wavelengthranging from 185 to 400 nanometers.
 18. The method of claim 13, whereinthe visible light emitted from the visible light source has an angle ofdivergence of ten degrees or less.
 19. The method of claim 13, whereinthe reflective inner surface of the air duct includes a reflectance ofat least fifty percent.
 20. The method of claim 13, wherein thereflective inner surface of the air duct includes a reflectance of atleast ninety-nine percent.
 21. The method of claim 13, wherein the airduct further comprises one or more air valves disposed along a main bodyof the air duct.